Constant volume sampling system

ABSTRACT

A constant volume sampling system is provided, comprising a sample loop including a section of tubing having a predetermined volume and having a first end and a second end; a first valve having a first port, connectable to a process line .Iadd.at a first point.Iaddend., a second port connected to the first end of the sample loop, a third port, connectable to a pressurized gas line, and a selector for selectively establishing flow between the first and second ports or between the second and third ports; a second valve having a first port, connectable to the process line .Iadd.at a second point wherein a pressure differential exists in the process line between the first point and the second point.Iaddend., a second port, connected to the second end of the sample loop, a third port, connectable to a sample container, and a selector for selectively establishing flow between the first and second ports or between the second and third ports; an actuator, for operating the first valve and the second valve; and a linkage, for linking the actuator and the first and second valves such that the actuator operates the first and second valves simultaneously, the linkage being operably connected externally of the sample loop to the first valve, the second valve and the actuator. A method is provided for operating the system so as to neutralize a hazardous sample as it is taken by placing a neutralizing substance in the sample container before the sample is taken.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to sampling systems which remove asample from a process line containing a flowing fluid and, moreparticularly, to sampling systems which remove a specified volume offluid from a process line.

2. Prior Art

There are many types of devices which remove samples from process lines.R. Wilson Spencer's prior U.S. Pat. Nos. 4,651,574, 4,791,821, 4,800,761and 4,879,915 are examples of such devices. In specialized situations,often having a specified volume, with each successive sample having thesame specified volume. It is tedious and sometimes dangerous to measurea specific volume of fluid into a sample container using standardsampling systems. In the case of hazardous fluid sampling, it is usuallydesirable to obtain a sample having a very small volume in order tolimit exposure to the substance as well as limit the amount ofneutralizing substance which must be added to the sample for safehandling in the lab.

In order to meet the sampling criteria set out above, prior art samplershave used a pair of three-way valves which are connected by a samplecylinder. One valve is connected to the process line and a pressurizedgas source, usually an inert gas such as nitrogen. The second valve isconnected to the process line and to a vented sample container. Theoperational parts of the valves are connected through the samplecylinder by a rotatable shaft which allows the valves to be operatedsimultaneously. Thus, a flow is established from the process linethrough the sample cylinder and back to the process line. Manipulationof the valves shuts off the flow from the process line, trapping asample in the cylinder. Further operation of the valves allows thesample to be ejected from the cylinder by the pressurized gas into thesample container. The container is then removed and taken to a lab foranalysis (and neutralization, if hazardous).

Prior art samplers do not facilitate easy changing of sample volumes.For example, if the operator desires to change from a 100 cc samplevolume to a 50 cc sample volume, the sample cylinder and shaft (which isconnected through the cylinder) must be removed requiring completedisassembly of the sampling system. Further, as the desired samplevolume decreases, it is difficult to find standard sample cylinders.[.haVing.]. .Iadd.having .Iaddend.such small volumes which also haveroom for the internal shaft connecting the two valves. In addition tothe above problems, cleaning of the prior art systems is impossiblewithout disassembly, and the shaft is contaminated during operation.Also, plugging of the sample passageways is possible due to therestrictions caused by the narrow clearance of the shaft within thecylinder, as well as shaft connections within the valves.

SUMMARY OF THE INVENTION

Therefore, it is an object of this invention to provide a constantvolume sampling system which separates the linkage between valves fromthe passageways which transmit sample flow.

It is another object of this invention to provide a constant volumesampling system which allows for easy changing of sample volumes.

It is still another object of this invention to provide a constantvolume sampling system which will handle small volume samples.

It is a further object of this invention to provide a constant volumesampling system which is compact, simple to operate and easy to clean.

It is a further object of this invention to provide a constant volumesampling system in accordance with the above objects and which isremotely operable.

It is another object of this invention to provide a constant volumesampling system which allows the operator to neutralize the sample as itis being taken, without exposure to the operator.

Accordingly, a constant volume sampling system is provided, comprising asample loop including a section of tubing having a predetermined volumeand having a first end and a second end; a first valve having a firstport, connectable to a process line .Iadd.at a first point.Iaddend., asecond port connected to the first end of the sample loop, a third port,connectable to a pressurized gas line, and a selector for selectivelyestablishing flow between the first and second ports or between thesecond and third ports; a second valve having a first port, connectableto the process line .Iadd.at a second point wherein a pressuredifferential exists in the process line between the first point and thesecond point.Iaddend., a second port, connected to the second end of thesample loop, a third port, connectable to a sample means, and a selectorfor selectively establishing flow between the first and second ports orbetween the second and third ports; an actuator, for operating the firstvalve and the second valve; and a linkage, for linking the actuator andthe first and second valves such that the actuator operates the firstand second valves simultaneously, the linkage being operably connectedexternally of the sample loop to the first valve, the second valve andthe actuator. A method is provided for operating the system so as toneutralize a hazardous sample as it is taken by placing a neutralizingsubstance in the sample container before the sample is taken.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an embodiment of the invention.

FIG. 2 is a sectional top view of the invention taken along line 2--2 ofFIG. 1.

FIG. 3 is the same view as FIG. 2, but of an alternate embodiment of theinvention having a remote valve actuator.

FIG. 4 is a sectional view of the invention taken along line 4--4 ofFIG. 2.

FIG. 5 is a sectional back view of the invention taken along line 5--5of FIG. 2.

FIG. 6 is a schematic depiction of the invention.

FIG. 7 is the same view as FIG. 4, but of an alternate embodiment of theinvention in which the selector means of one valve includes the actuatormeans of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

As shown in the Figures, the invention 1 includes several basic parts.The sampling operation is accomplished using two three-way valves, suchas the Hoke Model 7165 F4Y three-way ball valve or equivalent. A firstvalve 2 is connected to a process line (not shown) via inlet process tapline 3, to a pressurized gas line 4 and to a sample loop 5. A secondvalve 6 is connected to the process line via outlet process tap line 7,to a sample means 8, for receiving a sample, and to sample loop 5.Actuator means 9 allows first valve 2 and second valve 6 to be operatedsimultaneously, via linkage means 10, which operates externally ofsample loop 5.

The system 1 is preferably installed on a fixed surface 11 near thepoint where the process line is tapped. A mounting bracket 12 isattached to fixed surface 11, as shown in FIGS. 1 and 2, by mountingbracket screws 13 or bonded by other means such as welding. As shown inFIG. 2, mounting bracket 12 can have a channel shape so as to encase andprotect valves 2 and 6 as well as sample loop 5. Valves 2 and 6 aremounted through holes in mounting bracket 12 and held in place by firstvalve nut 14 and second valve nut 15. Actuator means 9 is also attachedto mounting bracket 12. When actuator means 9 is equipped with actuatorstem 16, actuator stem 16 is rotatably mounted in bearing 17 on mountingbracket .[.!2.]. .Iadd.12 .Iaddend.and is held in place by snap ring 18.Additional protection of components is provided by face bracket 19,which is attached to mounting bracket 12 by face bracket screws 20 orother bonding means such as welding. Face bracket 19 protects andencases linkage means 10, and provides a surface 21 on which theposition of actuator means 9 may be indicated. Actuator stem 16 is alsorotatably mounted in bearing 22 on face bracket 19, and is held in placeby snap ring 23.

First valve 2 has a first port 24 connectable to inlet process tap line3 at fitting 27; a second port 25 connected to sample loop 5 at fitting28; and a third port 26 connectable to pressurized gas line 4 at fitting29. Likewise, second valve 6 has a first port 30 connectable to outletprocess tap line 7 at fitting 33; a second port 31 connected to sampleloop 5 at fitting 34 and a third port 32 connectable to sample means 8at fitting 35. Each valve 2,6 has a selector means 36 for selectivelyestablishing flow between first port 24,30 and second port 25,31 orbetween second port 25,31 and third port 26,32. Selector means 36includes the typical inner workings of the three-way ball valves 2,6described above, operated by valve stems 37 and 38. However, other typesof valves and selector means known in the art may suffice, so long asthe flow is directed as described herein.

Thus, when valve stem 37 is turned, first valve 2 will move from a firstposition connecting inlet process tap line 3 and sample loop 5 to asecond position connecting pressurized gas line 4 and sample loop 5.When valve stem 38 is turned, second valve 6 will move from a firstposition connecting outlet process tap line 7 and sample loop 5 to asecond position connecting sample means 8 and sample loop 5. FIG. 6schematically illustrates the flow induced by the various positions ofvalves 2 and 6 utilizing flow arrows 39-44. When valves 2,6 are in thefirst position described above, the fluid flow follows flow arrows 39,40 and 41, establishing a representative flowing sample in sample loop5. As valves 2,6 are moved to the second position, a sample of theprocess fluid is first trapped in sample loop 5. Then, as valve 2, 6reach the second positions, pressurized gas pushes the sample fromsample loop 5 into sample means 8, with the gas being vented throughvent line 45, the flow following flow arrows 42, 40, 43 and 44.

It is necessary that both valves 2,6 operate simultaneously in order toproperly eject a sample into sample means 8. Actuator means 9 andlinkage means 10 accomplish this task. The key is to move the valves 2,6between first and second positions externally of sample loop 5 in orderto eliminate prior art linkages. Preferred embodiments of actuator means9 and linkage means 10 are shown in FIGS. 1-5. As shown in FIGS. 1 and2, actuator means 9 may comprise an actuator stem 16, rotatably attachedto mounting bracket 12 and face bracket 19, and an actuator handle 46,fixedly attached to stem 16 outside of face bracket 19. Flange 47extends from face bracket 19 to protect handle 46.

Linkage means 10 is shown in detail in FIG. 4, and preferably includes achain drive arrangement which allows valves 2,6 to be operated byactuator means 9 externally of sample loop 5. A first sprocket 48 isfixedly attached to actuator stem 16 between mounting bracket 12 andface bracket 19. A second sprocket 49 is fixedly attached to valve stem37 of first valve 2 in the same plane as first sprocket 48. A thirdsprocket 50 is fixedly attached to valve stem 38 of second valve 6 inthe same plane as first sprocket 48. Chain 51 is operably attachedaround sprockets 48, 49 and 50, as shown. Tension on chain 51 ismaintained by idler sprocket 52, which is rotatably attached to idlerstem 53. Idler stem 53 is fixedly attached to idler plate 54. Idlerplate is pivotally attached to mounting bracket 12 by idler screw 55.Sprockets 48, 49 and 50 should be the same size, such that movement ofchain 51 will exert simultaneous, identical rotation of valve stems 37and 38.

As shown in FIG. 7, actuator means 9 may be included as part of oneselector means 36 of one of the valves 2, 6. As shown, valve stem 37 ofvalve 2 can extend through face bracket 19, and handle 46 attachedthereto. Thus, chain 51 attaches to sprockets 49, 50 and 52 only,eliminating the need for a separate sprocket 48 for actuator means 9.However, this embodiment may not prove as versatile when it is necessaryto service valves 2, 6 frequently, since disassembly of valve 2 fromface bracket 19 is required.

In order to calibrate the system 1, valves 2,6 are adjusted to the firstposition described above. Idler sprocket 52 is urged against chain 51and idler screw 55 is tightened, thus maintaining chain tension.Rotation of handle 46 will now rotate valve stems 37,38. In theembodiment shown in FIG. 1, the pointer 56 of handle 46 is between firstposition, denoted by the number 57 and second position, denoted by thenumber 58. In practice, face bracket 19 should be marked with terms suchas "CIRCULATE" at first position 57 and "SAMPLE" at second position 58.Stop pins 59 extend outward from face bracket 19. Handle stop 60 extendsinward from handle 46 toward face bracket 19. Stop pins 59 arepositioned such that handle stop 60 will strike them and stop handlerotation when handle 46 reaches first position 57 or second position 58.

An alternate embodiment of the system 1 is shown in FIG. 3, whereinhandle 46 is replaced by a remote valve actuator 61, fixedly attached toface bracket 19 by mounting hardware 62, which will automatically rotateactuator stem 16 between first position 57 and second position 58.Remote actuator 61 may take any form known in the art, such as the HokeSelectomite valve actuator, part number 0112Y6F. Actuator means 9 couldinclude dual remote actuators 61 (not shown) connected to valves 2, 6.In such a situation, linkage means 10 could comprise electronic,pneumatic or other types of linkages between valves 2, 6.

Sample loop 5 is sized to provide an accurate sample size, and includesa section of tubing 63, as shown. The tubing 63 may be made of metal,plastic or other material as dictated by sampling needs. The use oftubing 63 allows for a great deal of flexibility in sample size andspace considerations. As shown, tubing 63 is looped to conserve space.The looped arrangement of sample loop 5 allows relatively large samplesto be obtained if desired. Of course, for very small samples, a short,small diameter piece of tubing 63 can be installed, eliminating the needfor special sample cylinders. Tubing 63 is easily and quickly changeableby simply uncoupling fittings 28 and 3 and replacing sample loop 5.

Sample means 8 may take any form known in the art. The arrangement shownis described in greated detail in U.S. Pat. No. 4,651,574. The sampleflows through fitting 35 into sample container 64. Shroud 65 and shroudbase 66 protect the container 64 from breakage. Safety chain 67 preventsloss of shroud base 66. In the embodiment shown, an integral ventedneedle 68 is included in fitting 35. Needle 68 pierces a septum 69 atthe top of container 64 when container 64 is installed. Needle 68 hastwo passageways. One is connected through fitting 35 to third port 32 ofsecond valve 6, and conducts fluid into container 64. The otherpassageway is connected through fitting 35 to vent line 45. Thus, when asample is forced into container 64 by pressurized gas, the gas is ventedthrough vent line 45. An absorber (not shown) or gas trap (not shown)may be added to vent line 45 for environmental protection. Of course,the type of sample means 8 shown is only an example. Any suitablecontainer known in the art may be used with the system 1.

Operation of the system 1 is simple. The system 1 is installed asdescribed above. Inlet process tap line 3 and outlet process tap line 7are connected to a process line (not shown) at points such that thepressure at tap line 3 is greater than that at tap line 7, in order toestablish flow through the system. Typical locations are on either sideof an orifice plate or pump. Also, a pump could be installed in eithertap line 3,7 in order to create flow in the system 1. Once the system 1is installed and with the system in first position 57, a sample means 8is connected to sample fitting 35. Actuator means 9 is then moved tosecond position 58. The sample from sample loop 5 is discharged intosample means 8. Actuator means 9 is returned to first position 57, andsample container 64 is removed from sample means 8 and taken to the lab.

For sampling of hazardous substances requiring neutralization, such asphosgene, a neutralizing substance 70 is placed in sample means 8 priorto sampling. Since the volume of the sample is known, the proper volumeof neutralizing substance 70 can be premeasured. When the sample istaken, it is therefore immediately neutralized without exposure topersonnel and without danger of exposure during transportation to thelab, even if sample container 64 is dropped and broken.

As can be seen, a constant volume sampling system is described hereinwhich provides a simple and efficient way to obtain a homogeneous sampleof a desired volume. The linkage means 10 of the system 1 is notcontaminated by the sample being taken. Sample volume can be changedquickly and easily by changing sample loop 5. The system 1 is compactand easy to install, and can be operated remotely. A neutralizingsubstance 70 can be put into the sample container 64 prior to samplingto assure safety. Many other embodiments of the invention will occur tothose skilled in the art, and are intended to be included within thescope and spirit of the following claims.

I claim:
 1. A constant volume sampling system, comprising:a. a sampleloop including a section of tubing having a predetermined volume andhaving a first end and a second end; b. a first having a first port,connectable to a process line at a first point, a second port connectedto said first end of said sample loop, a third port, connectable to apressurized gas line, and a selector means for selectively establishingflow between said first and second ports or between said second andthird ports; c. a second valve having a first port, connectable to saidprocess line at a second point wherein the pressure in said process lineis less than the pressure at said first point, a second port, connectedto said second end of said sample loop, a third port, connectable to asample means for receiving a sample, and a selector means forselectively establishing flow between said first and second ports orbetween said second and third ports; d. an actuator means, for operatingsaid first valve and said second valve; and e. a linkage means, formechanically linking said actuator means and said first and second valvesuch that said actuator means operates said first and second valvessimultaneously, said linkage means being .[.operable.]. .Iadd.operably.Iaddend.connected externally of said sample loop to said first valve,said second valve and said actuator means.
 2. A constant volume samplingsystem according to claim 1, wherein said linkage means includes a firstsprocket operably connected to said actuator means, a second sprocketoperably connected to said selector means of said first valve, a thirdsprocket operably connected to said selector means of said second valve,and a chain, operably connected to said first sprocket, said secondsprocket and said third sprocket.
 3. A constant volume sampling systemaccording to claim 2, further comprising:f. a mounting bracket, fixedlyconnected to said first valve and said second valve.
 4. A constantvolume sampling system according to claim 3, wherein said selector meansof said first valve includes a first valve stem and said selector meansof said second valve includes a second valve stem and said actuatormeans includes an actuator stem, and wherein said first sprocket isfixedly attached to said first valve stem and said second sprocket isfixedly attached to said second valve stem and said third sprocket isfixedly attached to said actuator stem.
 5. A constant volume samplingsystem according to claim 4, wherein said actuator stem is rotatablyconnected to said mounting bracket.
 6. A constant volume sampling systemaccording to claim 5, wherein said actuator means includes a handlemounted on said actuator stem.
 7. A constant volume sampling systemaccording to claim 5, further comprising:g. a face bracket, fixedlyconnected to said mounting bracket so as to encase said linkage means,said face bracket including an opening through which said actuator stempasses.
 8. A constant volume sampling system according to claim 7,wherein said actuator means includes a handle mounted on said actuatorstem exterior of said face bracket.
 9. A constant volume sampling systemaccording to claim 8, further comprising:h. a handle stop, fixedlyattached to and extending from said handle toward said face bracket; i.a first position stop, fixedly attached to said face bracket andextending toward said handle to a point wherein said first position stopwill block movement of said handle stop when said handle is in a desiredfirst position; and j. a second position stop, fixedly attached to saidface bracket and extending toward said handle to a point wherein saidsecond position stop will block movement of said handle stop when saidhandle is in a desired second position.
 10. A constant volume samplingsystem according to claim 7, wherein said actuator means furtherincludes a remote valve actuator, operably connected to said actuatorstem.
 11. A constant volume sampling system according to claim 1,further comprising:f. a mounting bracket, fixedly connected to saidfirst valve and second valve.
 12. A constant volume sampling systemaccording to claim 1, further comprising:f. a sample means for receivinga sample, connectable to said third point of said second valve, andwherein said sample means includes a sample container with aneutralizing substance contained therein.
 13. A constant volume samplingsystem according to claim 1 wherein said selector means of said firstvalve includes said actuator means.
 14. A constant volume samplingsystem according to claim 1 wherein said selector means of said secondvalve includes said actuator means.
 15. In a constant volume samplingsystem, comprising:a. a sample loop including as section of tubinghaving a predetermined volume and having a first end and a second end;b. a first valve having a first port, connected to a process line at afirst point, a second port connected to said first end of said sampleloop, a third port, connected to a pressurized gas line, and a selectormeans for selectively establishing flow between said first and secondports or between said second and third ports; c. a second valve having afirst port, connectable to a process line at a second point wherein thepressure in said process line is less than the pressure at said firstpoint, a second port, connected to said second end of said sample loop,a third port, connected to a sample means for receiving a sample, and aselector means for selectively establishing flow between said first andsecond ports or between said second and third ports; d. an actuatormeans for operating said first valve and said second valve; e. a linkagemeans, for linking said actuator means and said first and second valvessuch that said actuator means operates said first and second valvessimultaneously, said linkage means being operably connected externallyof said sample loop to said first valve, said second valve and saidactuator; and f. a sample means for receiving a sample, connected tosaid third port of said second valve, said sample container having aneutralizing substance contained therein; a method for gathering asample of a hazardous fluid flowing in said process line, comprising thesteps of:a. positioning said actuator means in a first position so as toestablish flow of said fluid from said first point in said process linethrough said sample loop to said second point in said process line; andmoving said actuator means to a second position thereby trapping asample of said fluid in said sample loop and allowing pressurized gasfrom said pressurized gas line to force said sample from said sampleloop into said neutralizing substance in said sample means. .Iadd.
 16. Aconstant volume sampling system, comprising:a. a sample loop including asection of tubing having a predetermined volume and having a first endand a second end; b. a first valve having a first port, connectable to aprocess line at a first point, a second port connectable to said firstend of said sample loop, a third port, connectable to a pressurized gasline, and a selector means for selectively establishing flow betweensaid first and second ports or between said second and third ports; c. asecond valve having a first port, connected to said process line at asecond point wherein a pressure differential exists in said process linebetween said first point and said second point, a second portconnectable to said second end of said sample loop, a third port,connectable to a sample means for receiving a sample, and a selectormeans for selectively establishing flow between said first and secondports or between said second and third ports; d. an actuator means, foroperating said first valve and said second valve; and e. a linkagemeans, for mechanically linking said actuator means and said first andsecond valves such that said actuator means operates said first andsecond valves simultaneously, said linkage means being operablyconnected externally of said sample loop to said first valve, saidsecond valve and said actuator means. .Iaddend. .Iadd.17. In a constantvolume sampling system, comprising: a. a sample loop including a sectionof tubing having a predetermined volume and having a first end and asecond end; b. a first valve having a first port, connectable to aprocess line at a first point, a second port connectable to said firstend of said sample loop, a third port, connectable to a pressurized gasline, and a selector means for selectively establishing flow betweensaid first and second ports or between said second and third ports; c. asecond valve having a first port, connectable to said process line at asecond point wherein a pressure differential exists in said process linebetween said first point and said second point, a second portconnectable to said second end of said sample loop, a third port,connectable to a sample means for receiving a sample, and a selectormeans for selectively establishing flow between said first and secondports or between said second and third ports; d. an actuator means, foroperating said first valve and said second valve; e. a linkage means,for linking said actuator means and said first and second valves suchthat said actuator means operates said first and second valvessimultaneously, said linkage means being operably connectable externallyof said sample loop to said first valve, said second valve and saidactuator; and f. a sample means for receiving a sample, connectable tosaid third port of said second valve, said sample container having aneutralizing substance contained therein;a method for gathering a sampleof hazardous fluid flowing in said process line, comprising the stepsof: a. positioning said actuator means in a first position so as toestablish flow of said fluid through said sample loop between said firstpoint in said process line and said second point in said process line;and b. moving said actuator means to a second position thereby trappinga sample of said fluid in said sample loop and allowing pressurized gasfrom said pressurized gas line to force said sample from said sampleloop into said neutralizing substance in said sample means. .Iaddend.